1. Field of the Invention
The present invention relates to variants of a parent phytase, in particular variants of improved thermostability and/or specific activity. The invention also relates to DNA sequences encoding such variants, their production in a recombinant host cell, as well as methods of using the variants, in particular within the field of animal feed. A preferred parent phytase is the Peniophora phytase comprising SEQ ID NO: 2.
2. Description of Related Art
EP 897010 entitled “Modified phytases” discloses, i.a., certain variants of an Aspergillus fumigatus phytase. EP 897985 entitled “Consensus phytases” discloses, i.a., a fungal consensus phytase which may be designed on the basis of, i.a., a multiple alignment of several ascomycete phytases. WO 99/48380 entitled “Thermostable phytases in feed preparation and plant expression” relates to certain aspects of using thermostable phytases. Examples of thermostable phytases are the various consensus phytases listed at p. 30 below the bold line. WO 00/43503 entitled “Improved phytases” relates i.a. to certain phytase variants of increased thermostability, which may be designed by a process similar to the one described in EP 897985. Examples of thermostable phytases are shown at p. 54-55 below the bold line. These phytases all have a percentage of identity to SEQ ID NO: 2 of below 75%.
WO 98/28408 discloses a phytase derived from Peniophora lycii. WO 99/49022 discloses certain variants of Peniophora lycii phytase.
It is an object of the present invention to provide novel and improved phytase variants, in particular of improved thermostability and/or increased specific activity.